In known steam power plants, operating steam for a steam turbine is generally generated in a steam generator, the energy contained in a hot gas being released to one or more heat exchangers which are fed with water, so that operating steam can be generated by heating this water, or which are fed with steam, so that the steam can be superheated by means of a said heat exchanger; superheating of this type, in known steam turbines, takes place, for example, between a high-pressure stage and a medium-pressure stage of the steam turbine, the steam which leaves the high-pressure stage being superheated by means of a reheater heating surface arranged in the steam generator and being fed to the medium-pressure stage.
This reheating of the steam makes a contribution, for example, to increasing the efficiency of the steam turbine.
In known steam power plants, thermal energy is supplied in order to generate and/or reheat steam by means of heat exchanger surfaces which are arranged in the steam generator and come into contact with a hot gas guided in the steam generator. The heated heat exchanger surfaces in turn release their thermal energy to water and/or steam guided inside the body formed by a heat exchanger surface. The heating is therefore realized by means of heat transfer from the hot gas to the heat exchanger surface and from the heat exchanger surface to the medium that is to be heated.
Since in the heat exchangers which are known from the prior art and are used in steam generators of known steam power plants the energy of a hot gas is transferred to the medium to be heated by means of a material of the heat exchanger surface that has been heated by the hot gas, the quantity of energy which can be transferred to the medium to be heated, for example water and/or steam, is limited by the materials properties of the heat exchanger surface.
Therefore, in known steam power plants, the permissible steam temperatures are limited, since the heat exchanger surface which transfers the thermal energy cannot be heated to any desired temperature level on account of its material properties and associated thermal loading limits.
Furthermore, the transfer of heat from hot gas to the medium that is to be heated is subject to a delay caused substantially by the required heating time of the heat exchanger surface.